A multiplicity of devices have been employed to deter or prevent alteration of photographic identification cards and other indicia containing substrates. More notably, protective devices for security identification cards, particularly those bearing a photograph of its holder, are employed to eliminate tampering or fraudulent alteration of the card, photograph or both.
Unprotected photographic images are rather simple targets for alteration. Should the forger wish to substitute a photograh of another individual for that originally contained on the card, a portion of the photograph can simply be excised from the card and substituted with a new image. One technique for hampering a forger includes the use of filaments placed across the face or some other portion of the security identification card. Often such filaments are laminated directly above the photograph or photographic likeness of the card holder to deter a forger from altering the card. Although providing some security against intentional tampering, a careful and intent forger can alter a card by excising the original photograph, substituting a new image therefor, and matching the alignment of substituted filament portions. Such changes in the hands of a skilled forger may be undetectable to the naked eye.
In order to improve tamper resisting characteristics of security cards, security filaments have been modified as depicted in the patent literature. For example, Von Kempski, U.S. Pat. No. 4,371,196, provides a filament with a structural cross-section. More specifically, the filament is composed of metal which includes notches thereon conforming to a predetermined code. This filament is generally laminated between a card cover and photograph of the card holder. An electronic coding system is used to determine whether or not the card has been altered. If altered, the code contained on the filament will probably not match that of the original, and, therefore, the forgery can be detected. Tooth, U.S. Pat. No. 4,183,989, discloses a polyester thread with two machine varifiable features. The polyester is coated with luminescent, X-ray absorbent, and/or metal magnetic material designed to be read by a sophisticated electronic device. These two patents are indicative of a trend which includes the use of elaborate detection systems to insure the integrity of security identification cards.